New Button
- check if there is existing scenario
- pop up dialog confirming to "Discard", "save", "cancel"

Load
+ GUI to input string

Save
+ GUI to show the text string

Adding object
+ tooltip to say names
- make sure that objects are not dropped in the palette

Delete object
- remove objects from QueueApp.models, QueueApp.views


Queue
- number of servers?
- queue discipline?
- bounded queue?

Monitor
- check which statistics must be shown

Sim
- check standard deviation